Replace SpoolBuddy self-update with SSH-based updates from Bambuddy

The daemon's self-update mechanism (git fetch/reset on its own code) was
  fragile: .git permission errors, self-modifying code mid-run, hardcoded
  main branch. Bambuddy now SSHes into the SpoolBuddy Pi and drives the
  update remotely — matching its own branch, with step-by-step progress
  via WebSocket. Install script updated with SSH access, sudoers entry,
  and --ssh-pubkey flag for pairing.

.gitignore

@@ -64,6 +64,9 @@ data/
 # JWT secret file (should be in data dir, but protect project root too)
 .jwt_secret
 
+# SpoolBuddy SSH keys (generated at runtime for remote updates)
+spoolbuddy/ssh/
+
 # Security scan output
 *.sarif